Almost every technology vendor releases regular security updates and Apple is no exception. Apple recently release an update to fix a bug. The bug, according to Apple, could allow for a malicious application to bypass Gatekeeper, which is a technology that ensures by default that only trusted software runs on a user's Mac. It affects all recent versions of the operating system. For more information on macOS 11.3 you can visit the support site: https://support.apple.com/en-us/HT212325.